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Displasia fibrosa : caso clínico e revisão de literatura
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A displasia fibrosa representa uma lesão osteofibrosa intramedular benigna provocada por uma anomalia
displásica do tecido mesenquimatoso que inviabiliza o processo de remodelação de tecido ósseo primário
a tecido ósseo lamelar maduro. O processo de modelação óssea encontra-se igualmente alterado,
condicionando uma falha no realinhamento das trabéculas ósseas. [1] [2] [3]
As lesões ósseas características da doença representam 5% a 7% dos tumores ósseos benignos. Afeta
igualmente ambos os géneros e todas as etnias. (1) (2) (4)
Pode surgir sob a forma de doença monostótica (75%) ou poliostótica (20-30%). A Síndrome de McCune-
Albright, com manchas cutâneas café-au-lait e alterações endocrinológicas, afeta 3% dos doentes
portadores de displasia fibrosa poliostótica. Em 1% dos doentes com displasia fibrosa surgem associados
mixomas intramusculares (Síndrome de Mazabraud). [4]
Estudos moleculares sugerem que uma mutação somática precoce na vida embrionária cause o mosaicismo
genético. O gene localiza-se na banda 20q13, uma área que codifica a subunidade α da proteína G. Mutações
ativadoras desta subunidade foram identificadas quer na forma monostótica, quer poliostótica, e parecem
ser etiologicamente importantes na displasia fibrosa. [4] [5]
As lesões ósseas são geralmente detetadas antes dos 30 anos, apesar de as manifestações clínicas poderem
surgir previamente. [2] O espectro de severidade da displasia fibrosa é amplo. A dor óssea é, frequentemente,
a primeira e única manifestação da displasia fibrosa. Outras manifestações são deformidade óssea, fraturas
e alterações neurológicas por compressão nervosa. [6] [7]
O prognóstico da doença baseia-se na localização das lesões e severidade das mesmas. A transformação
maligna na displasia fibrosa é rara, ocorrendo em 1% dos doentes.
O tratamento da displasia fibrosa poderá requerer terapêutica médica e/ou cirúrgica. Não existem critérios
definidos para a necessidade de intervenção cirúrgica dependendo, sobretudo, da gravidade da doença.
Apresentamos o caso clínico de uma doente de 13 anos com displasia fibrosa monostótica no fémur, tendo
sido sujeita a tratamento cirúrgico.
Fibrous dysplasia is a benign intramedullary osteofibrous lesion caused by a dysplastic anomaly of the mesenchymal tissue that prevents the process of remodeling of primary bone tissue into lamellar bone. Failure in the realignment of the skeletal bone is due to the change of the bone modeling mechanism. (1)(2)(3) The fibrous dysplastic lesions account for 5% to 7% of benign bone tumors. It equally affects both genders and all ethnic groups. (1) (2) (4) It may occur as a monostotic (75%) or polyostotic (20-30%) disease. McCune-Albright syndrome affects 3% of patients with polyostotic fibrous dysplasia. Intramuscular myxomas (Mazabraud Syndrome) appear in 1% of patients with fibrous dysplasia. (4) Molecular studies suggest that an early somatic mutation in embryonic life causes a genetic mosaicism. The gene is located at 20q13, an area that encodes the α subunit of the G protein. Activating mutations of the α-subunity of the G-protein have been identified in monostotic and polyostotic form and appear to be etiologically relevant in fibrous dysplasia. (4) (5) Bone lesions are usually detected before the age of 30, although clinical manifestations may arise earlier. The severity of fibrous dysplasia is variable. Bone pain is often the first and only manifestation of fibrous dysplasia. Other manifestations are bone deformity, fractures and neurological symptoms due to nerve compression. (2) (6) (7) Prognosis is based on the location of the lesions and their severity. Malignant transformation is rare, occurring in 1% of patients. Treatment of fibrous dysplasia may require medical and/or surgical therapy. There are no defined criteria for surgical intervention depending mainly upon the severity of the disease. We describe the case of a 13-year-old patient with monostotic fibrous dysplasia of the femur that underwent surgical treatment.
Fibrous dysplasia is a benign intramedullary osteofibrous lesion caused by a dysplastic anomaly of the mesenchymal tissue that prevents the process of remodeling of primary bone tissue into lamellar bone. Failure in the realignment of the skeletal bone is due to the change of the bone modeling mechanism. (1)(2)(3) The fibrous dysplastic lesions account for 5% to 7% of benign bone tumors. It equally affects both genders and all ethnic groups. (1) (2) (4) It may occur as a monostotic (75%) or polyostotic (20-30%) disease. McCune-Albright syndrome affects 3% of patients with polyostotic fibrous dysplasia. Intramuscular myxomas (Mazabraud Syndrome) appear in 1% of patients with fibrous dysplasia. (4) Molecular studies suggest that an early somatic mutation in embryonic life causes a genetic mosaicism. The gene is located at 20q13, an area that encodes the α subunit of the G protein. Activating mutations of the α-subunity of the G-protein have been identified in monostotic and polyostotic form and appear to be etiologically relevant in fibrous dysplasia. (4) (5) Bone lesions are usually detected before the age of 30, although clinical manifestations may arise earlier. The severity of fibrous dysplasia is variable. Bone pain is often the first and only manifestation of fibrous dysplasia. Other manifestations are bone deformity, fractures and neurological symptoms due to nerve compression. (2) (6) (7) Prognosis is based on the location of the lesions and their severity. Malignant transformation is rare, occurring in 1% of patients. Treatment of fibrous dysplasia may require medical and/or surgical therapy. There are no defined criteria for surgical intervention depending mainly upon the severity of the disease. We describe the case of a 13-year-old patient with monostotic fibrous dysplasia of the femur that underwent surgical treatment.
Descrição
Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2018
Palavras-chave
displasia fibrosa doença monostótica Doença poliostótica Síndrome de McCune- Albright Diagnóstico diferencial Ortopedia